1. Field of the Invention
The present invention relates to a light-emitting device including an organic EL element. The present invention also relates to a display device including an organic EL element. The present invention also relates to a light-emitting system including the light-emitting device. The present invention also relates to a display system including the display device.
2. Description of the Related Art
An organic EL element has been actively researched and developed. In the fundamental structure of the organic EL element, a layer containing a light-emitting organic compound is provided between a pair of electrodes. By voltage application to this element, light emission from the light-emitting organic compound can be obtained.
The organic EL element can be formed into a film shape; thus, a large-area element can easily be formed. Accordingly, the organic EL element has a high utility value as a surface light source that can be applied to lighting or the like.
For example, a lighting equipment including an organic EL element is disclosed in Patent Document 1.
Further, a display device in which an organic EL element and a thin film transistor are combined has been actively developed. A display device including an organic EL element does not need a backlight which is necessary for a liquid crystal display device, so that a reduction in thickness and an increase in luminance and contrast can be achieved.